1. Field of the Invention
The present invention relates to digital broadcasting receivers and systems and, more particularly, to a digital broadcasting receiver and system capable of transmitting, using a one-channel transmission path, and reproducing a multiplexed picture that is formed by multiplexing a plurality of pictures.
2. Description of the Background Art
The non-interlace digital broadcasting system using the 525p sequential scanning method has been an example of the digital broadcasting system. The details of the non-interlace digital broadcasting system are disclosed, for example, in Urano et al., xe2x80x9cDevelopment of CS Digital Broadcasting System Prototype for 525-Progressive Scanning Signal,xe2x80x9d ITE Technical Report, Vol. 20, No. 13, pp. 25-30, Feb. 27, 1996.
The non-interlace digital broadcasting system provides broadcasting service by using picture data for the non-interlace scanning method that is different from the current interlace scanning (NTSC) method.
The inventor proposed a digital stereoscopic broadcasting system for transmitting and receiving right-eye and left-eye pictures, which are obtained by the interlace scanning method, along a one-channel transmission path by converting the pictures into a one-frame multiplexed picture for the non-interlace scanning method (Japanese Patent Laying-Open No. 10-174064). According to the digital stereoscopic broadcasting system, stereoscopic broadcasting service can be provided through a one-channel transmission path.
A transmitter of the digital stereoscopic broadcasting system alternately transmits odd and even fields of multiplexed picture data along a one-channel transmission path. Meanwhile, a receiver has to return the received, one-channel multiplexed picture to the right-eye and left-eye pictures for the two-channel interlace scanning method and appropriately format the pictures according to the field types.
However, the receiver does not have the function of determining whether a picture to be formatted corresponds to an odd field or an even field. It is therefore likely that an picture is reproduced and displayed with a mistaken exchange of odd and even fields. This problem occurs even when a picture other than a stereoscopic picture is to be transmitted by multiplexing.
An object of the present invention is to provide a digital broadcasting system capable of transmitting an encoded multiplexed picture along a one-channel path and properly reproducing and displaying the picture.
According to one aspect of the present invention, a digital broadcasting system includes a picture producing circuit for producing a plurality of multiplexed pictures each formed of a plurality of original pictures and encoding the plurality of multiplexed pictures to produce a plurality of encoded pictures, a transmitting circuit for transmitting an output of the picture producing circuit to a one-channel transmission path, a receiving circuit for receiving an output of the transmitting circuit through the one-channel transmission path, a decoder for decoding the plurality of encoded pictures received in the receiving circuit to reproduce the plurality of multiplexed pictures and sequentially outputting the pictures according to a displaying order, and a formatting circuit for formatting the reproduced multiplexed pictures output from the decoder based on a field type according to the displaying order, the field type being an even field or an odd field, and the picture producing circuit producing the plurality of encoded pictures so as to realize a prescribed correspondence between the field type and the displaying order.
Preferably, the plurality of multiplexed pictures include a multiplexed picture in the even field and a multiplexed picture in the odd field, the picture producing circuit includes a multiplexing circuit for alternately producing and outputting the multiplexed picture corresponding to the even field and the multiplexed picture corresponding to the odd field from a prescribed one of them, and an encoder for starting encoding from a multiplexed picture that is output first from the multiplexing circuit and adding reference data indicating the displaying order to each of the plurality of encoded pictures, and the formatting circuit adds, to the reproduced multiplexed picture, a synchronous signal corresponding to the even field or a synchronous signal corresponding to the odd field according to whether the reference data of the reproduced multiplexed picture is odd or even.
Preferably, the plurality of encoded pictures form a GOP structure based on the MPEG method, and the picture producing circuit encodes the plurality of multiplexed pictures so that a prescribed one of the even field and the odd field comes first in the displaying order when the pictures are decoded.
According to the digital broadcasting system of the present invention, the encoded pictures are produced so as to realize a prescribed correspondence between the field type and the displaying order based on a rule between the transmitting and receiving sides. Thus, the receiving side can discriminate the field type (odd and even fields) of the reproduced pictures by decoding the encoded pictures. As a result, proper formatting (that is, reproducing and displaying) can be made possible. Further, by multiplexing and encoding a plurality of original pictures based on a rule between the transmitting and receiving sides, the receiving side can properly format original pictures.
Another object of the present invention is to provide a digital broadcasting receiver capable of properly reproducing and displaying an encoded multiplexed picture received by using a one-channel path.
According to another aspect of the present invention, a digital broadcasting receiver includes a receiving circuit for receiving, through a one-channel transmission path, a plurality of encoded pictures that are produced by encoding a plurality of multiplexed pictures each including a plurality of original pictures, a decoder for decoding the received plurality of encoded pictures to reproduce the plurality of multiplexed pictures and sequentially outputting the pictures according to a displaying order, and a formatting circuit for formatting the reproduced multiplexed pictures output from the decoder based on a field type according to the displaying order, the plurality of encoded pictures each having reference data attached thereto indicating a displaying order, the field type being an even field or an odd field, and an encoded picture having prescribed reference data of the plurality of encoded pictures corresponding to a prescribed one of the even field and the odd field.
Preferably, the plurality of multiplexed pictures alternately include a multiplexed picture corresponding to the even field and a multiplexed picture corresponding to the odd field, an encoded picture having odd reference data of the plurality of encoded pictures corresponds to a prescribed one of the even field and the odd field, and the formatting circuit adds, to the reproduced multiplexed pictures, a synchronous signal corresponding to the even field or a synchronous signal corresponding to the odd field according to whether the reference data is odd or even.
Preferably, the plurality of multiplexed pictures are encoded so that a prescribed one of the even field and the odd field comes first in the displaying order when the pictures are decoded.
According to the digital broadcasting receiver of the present invention, the field type (odd and even fields) of a reproduced picture can be discriminated by decoding a received encoded picture based on a rule between the transmitting and receiving sides. Thus, proper formatting (that is, reproducing and displaying) can be made possible. Especially, the receiving side can properly format original pictures based on the rule between the transmitting and receiving sides even for such multiplexed pictures that are formed by multiplexing a plurality of original pictures.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.